U.S. Pat. No. 5,185,008 discloses a two-piece ostomy appliance in which one of the coupling rings is channel shaped and the other is provided with a substantially non-compressible insert that includes an axially-extending collar, a non-deformable wedge body, and a radially-extending pivot stem that centrally connects the collar and wedge body. The pivot stem allows limited forward and rearward rocking movement of the wedge body about a pivot axis extending through the stem. A massive front portion of the wedge body has an inwardly and rearwardly curved bearing surface of progressively increasing distance from the pivot axis so that the radial width of the insert decreases as the wedge body rocks rearwardly and increases as it rocks forwardly about the pivot axis. Ease of coupling is enhanced because rearward rocking of the wedge body decreases the width of the insert as it is being advanced into the channel of the other ring, and greater security is insured because forward rocking of the wedge body during the initial stages of ring separation effectively increases the radial width of the insert and thereby increases the resistance to ring separation.
Other references disclosing the state of the art are U.S. Pat. Nos. 4,872,869, 5,185,008, and 5,195,996, and European patent 0 463 359.
One aspect of this invention lies in providing a modified rocking wedge lock for the coupling rings of a two-piece ostomy appliance in which the rings, when coupled, are of relatively low profile and yet provide a highly secure locking and sealing action. In contrast to the construction disclosed in U.S. Pat. No. 5,185,008, the rings embodying this invention emit a clearly audible snapping or clicking sound as they are joined together, thereby signaling to the user that a secure and complete interconnection has been achieved.
The security of the interlock results partly from the fact that the walls of the channel-shaped coupling ring are relatively thick and resist outward flexure when the insert portion of the other locking ring, with its rocking wedge body, is inserted into the channel. In addition, the thick inner and outer side walls are of substantially the same length and have directly opposing rib means projecting into the channel at its entrance. The rib means of the outer wall is engagable with a bead along the collar portion of the insert element of the other ring and the rib means of the inner wall is engagable with a shoulder of the rocking wedge body, causing a forward rocking and wedging action of that body when axial forces of separation are applied to the rings. However, when a twisting force is selectively applied to the channel-shaped ring, with such force being exerted by pulling a tab extending radially outwardly from the channel ring's outer wall, such twisting may selectively initiate partial or complete uncoupling of the rings. Partial uncoupling may be used to vent and deflate a pouch of flatus gases, whereas complete uncoupling is undertaken when a pouch is to be removed and replaced, usually by a fresh pouch.
The rib means projecting into the channel from the inner wall is continuous and uninterrupted but, in preferred embodiments of the invention, the rib means of the outer wall is interrupted to define a notch or recess along an arcuate stretch in direct alignment with the pull tab. The channel ring may be provided with a plurality of such pull tabs, arranged in a circumferentially-spaced relation, in which case the rib means of the outer wall should have a plurality of notches, each pull tab being directly aligned with one of the notches. If desired, the rib means of the outer wall may have a multiplicity of uniformly-spaced notches about the full circumference of the wall with certain of such notches occurring even where no pull tabs are located.
The rib means of the outer wall adjacent each notch are preferably sharply undercut rather than rounded when viewed in radial section. More specifically, the rib of the outer wall has a rear surface that faces the channel and lies along a generally radial plane, an inner surface that faces inwardly towards the axis of the coupling ring, and an edge, preferably sharply defined, at the junction of the two surfaces. The sharply undercut surface of the rib latches against the bead of the other coupling ring (which is also sharply undercut) to enhance latching security as well as contribute in producing an audible clicking or snapping sound as the rings are coupled together.
In one preferred embodiment, each notch in the rib means of the outer wall has an inwardly facing surface that is flush with the remainder of the surface of the outer wall within the channel, thus resulting in a construction in which the wall is smooth and ribless for the full width of the notch. Since the notch is in direct alignment with a pull tab and preferably has a width or angular dimension approximating that of the tab, the notch facilitates intentional uncoupling of the rings when the channel-shaped ring is twisted in response to a pulling force applied to the tab. Full or partial disconnection of the rings commences when the bead of the faceplate ring slides out of the channel through the opening defined by the notch. The same result may be achieved by a second preferred embodiment in which the surface of each notch is not flush with that of the outer surface of the channel but instead is provided with a rounded shoulder of lesser height (measured radially) than the sharply undercut rib portions adjacent the notch.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings.